What is a painful localized muscle spasm called?

A painful localized muscle spasm is called a muscle cramp or charley horse. Cramps are involuntary, sudden contractions of one or more muscles that cause pain and stiffness. They can occur in any muscle in the body, but most commonly affect the muscles of the legs, feet, and hands. Muscle cramps can be caused by a number of factors, including dehydration, electrolyte imbalance, muscle fatigue, and nerve compression.